1. Field of the Invention
The present invention relates to a terminal having a conductive part and nonconductive part, and to a mobile terminal apparatus mounted with the terminal.
2. Description of the Related Art
Conventionally, telephone calls and transmission and reception of electronic mails with a cellular phone, and the like are widely used for communication with members of a family and friends. By using communication means such as telephone and electronic mail, one can easily contact any distant members of his or her family and friends whenever he or she wishes.
Further, in recent years, cellular phones and PDA (Personal Digital Assistant) are utilized not only as communication means, but also as image taking apparatuses for taking images of subjects computers for viewing Web sites, alarm clocks used on the road, or the like. With diversified applications of the mobile terminal apparatus such as a cellular phone and PDA, the number of various electronic parts mounted on the mobile terminal apparatus has increased and it has become necessary to provide the mobile terminal apparatus with a watertight function. Particularly, a gap between a housing of the apparatus and a battery terminal which is connected to a charger to supply electricity to a battery accommodated in the apparatus is required to be reliably shielded from water, because the battery terminal is exposed on the outer surface of the housing and is connected to various electronic parts in the apparatus.
Usually, a battery terminal is formed by attaching a conductive plate having a plus contact and a minus contact formed thereon and is fitted in a housing of the mobile terminal apparatus such that the plus and minus contacts are exposed in the opening of the housing. As a method to waterproof a gap between the battery terminal and opening, there has been used a technique that each of the plus and minus contacts is surrounded with a watertight member and then the watertight member is sandwiched between the housing and battery terminal (see, for example, Japanese Patent Laid-Open Nos. 6-26330, 10-144275, and 2001-185280).
However, in order to obtain reliable waterproofness as well as electric conductivity, a plate for a plus contact and that for a minus contact should be attached on the terminal substrate such that they are spaced apart and are surrounded by a watertight member, which results in an increased adhesive area and thus an increase in size of the apparatus. On the other hand, if an area to which the watertight member is to be attached is reduced in order to avoid increase in size of the apparatus, waterproofness deteriorates. Alternatively, if an exposed area of the plate is reduced in order to avoid increase in size of the apparatus without reducing the area to which the watertight member is attached, electric conductivity deteriorates.
Moreover, when a battery terminal is formed by attaching a plate onto a terminal substrate, it is difficult to make thickness of a plate and an adhesive agent completely uniform. In order to secure waterproofness of such a terminal having a non-uniform thickness, a thick watertight member should be attached onto a wide adhesive area, which results in increase in size of the apparatus.